Lithium secondary battery of high power property with improved high power density

ABSTRACT

Disclosed is a high-output lithium secondary battery including: a cathode that includes, as cathode active materials, a first cathode active material represented by Formula 1 below and having a layered structure and a second cathode active material represented by Formula 2 below and having a spinel structure, wherein the amount of the second cathode active material is between 40 and 100 wt % based on the total weight of the cathode active materials; an anode including amorphous carbon having a capacity of 300 mAh/g or greater; and a separator.

TECHNICAL FIELD

The present invention relates to a high-output lithium secondary batteryhaving enhanced power density characteristics. More specifically, thepresent invention relates to a high-output lithium secondary batteryincluding: a cathode that includes, as cathode active materials, a firstcathode active material represented by Formula 1 below and having alayered structure and a second cathode active material represented byFormula 2 below and having a spinel structure, wherein the amount of thesecond cathode active material is between 40 and 100 wt % based on thetotal weight of the cathode active materials; an anode includingamorphous carbon having a capacity of 300 mAh/g or greater; and aseparator.

BACKGROUND ART

As mobile device technology continues to develop and demand thereforcontinues to increase, demand for secondary batteries as energy sourcesis rapidly increasing. In addition, secondary batteries have recentlybeen used as power sources for electric vehicles (EVs), hybrid electricvehicles (HEVs), and the like. Accordingly, research into secondarybatteries that can meet a variety of demands is underway and, inparticular, demand for lithium secondary batteries having high energydensity, high discharge voltage and high output stability is increasing.

In particular, lithium secondary batteries used as power sources of EVsand HEVs require high-output characteristics that exhibit high outputwithin a short period of time.

Conventionally, a lithium cobalt composite oxide having a layeredstructure is generally used as a cathode active material of a lithiumsecondary battery. When a lithium cobalt composite oxide is used as acathode active material, however, cobalt as a main component is veryexpensive and output characteristics thereof are bad. Thus, lithiumsecondary batteries including such cathode active material are notsuitable for use in HEVs requiring high output because HEVs demand highoutput power from the batteries, particularly when starting from astandstill, rapidly accelerating, and the like.

Meanwhile, graphite is mainly used as an anode active material. However,graphite has poor properties and thus is not suitable for use as anenergy source for HEVs requiring high output.

Therefore, research into amorphous carbon as an anode active material isunderway. However, amorphous carbon has a low energy density, i.e., lessthan 300 mAh/g.

DISCLOSURE Technical Problem

The present invention aims to address the aforementioned problems of therelated art and to achieve technical goals that have long been waitingto be addressed.

Thus, an object of the present invention is to provide a lithiumsecondary battery that exhibits the same level of capacity and enhancedhigh-output characteristics and low-temperature characteristics whencompared to a lithium secondary battery using amorphous carbon.

Technical Solution

In accordance with one aspect of the present invention, provided is alithium secondary battery including a cathode active material including40 wt % or more of lithium manganese oxide based on the total weight ofthe cathode active material and amorphous carbon having a capacity of300 mAh/g or more as an anode active material.

In particular, a high-output lithium secondary battery according to thepresent invention includes: a cathode including, as cathode activematerials, a first cathode active material represented by Formula 1below and having a layered structure and a second cathode activematerial represented by Formula 2 below and having a spinel structure,in which the amount of the second cathode active material is between 40and 100 wt % based on the total weight of the cathode active materials;an anode including amorphous carbon having a capacity of 300 mAh/g ormore; and a separator.

Li_(x)(Ni_(v)Mn_(w)Co_(y)M_(z))O_(2-t)A_(t)   (1)

In Formula 1,

0.8≦x≦1.3, 0≦v≦0.9, 0≦w≦0.9, 0≦y≦0.9, 0≦z≦0.9, x+v+w+y+z=2, and 0≦t<0.2;M refers to at least one metal or transition metal cation having anoxidation number of +2 to +4; and A is a monovalent or divalent anion.

Li_(a)Mn_(2-b)M′_(b)O_(4-c)A′_(c)   (2)

In Formula 2, 0.8<a≦1.3, 0≦b≦0.5, and 0≦c≦0.3; M′ refers to at least onemetal or transition metal cation having an oxidation number of +2 to +4;and A′ is a monovalent or divalent anion.

The amorphous carbon may be one selected from the group consisting of afirst carbon having a specific surface area of 0.01 to 0.031 m²/mAh withrespect to capacity and a second carbon having a specific surface areaof 0.0035 to 0.017 m²/mAh with respect to capacity or a mixture thereof.When the first carbon and the second carbon are used in combination, aweight ratio of the first carbon to the second carbon may be in therange of 1:9 to 9:1.

In particular, the first carbon may be carbon having a powderconductivity of 15 S/cm or greater to less than 100 S/cm at a powderdensity of 1.0 to 1.2 g/cc, and the second carbon may be carbon having apowder conductivity of 30 S/cm or greater to less than 100 S/cm at apowder density of 1.4 to 1.6 g/cc.

The amounts of the first cathode active material having a layeredstructure of Formula 1 and the second cathode active material having aspinel structure of Formula 2 may be in the range of 10 wt % to 50 wt %and in the range of 50 wt % to 90 wt %, respectively, based on the totalweight of the first and second cathode active materials.

In a specific embodiment of the present invention, the first cathodeactive material may be a layered-structure lithium transition metaloxide having an average particle diameter of 0.03 to 0.1 μm/mAh withrespect to capacity and a powder conductivity of 1×10⁻³ S/cm or greaterto less than 10×10⁻³ S/cm at a powder density of 2.65 to 2.85 g/cc.

In addition, the second cathode active material may be aspinel-structure lithium manganese oxide having an average particlediameter of 0.1 to 0.2 μm/mAh with respect to capacity and a powderconductivity of 1×10⁻⁵ S/cm or greater to less than 10×10⁻⁵ S/cm at apowder density of 2.65 to 2.85 g/cc.

In a specific embodiment, the first cathode active material of Formula 1may be a layered crystalline structure lithium transition metal oxidesatisfying conditions that the oxide includes mixed transition metals ofNi and Mn, an average oxidation number of the total transition metalsexcluding lithium exceeds +3, and the amount of Ni is the same as thatof Mn on a molar ratio basis.

In addition, in another particular embodiment, the lithium transitionmetal oxide of Formula 1 may be Li(Ni_(0.5)Mn_(0.3)Co_(0.2))O₂ orLi(Ni_(1/3)Mn_(1/3)Co_(1/3))O₂.

In Formula 1, the transition metal such as Ni, Mn, or Co may besubstituted with a metal and/or other transition metal (M) elementshaving an oxidation number of +2 to +4. In particular, the transitionmetal may be substituted with at least one selected from the groupconsisting of Al, Mg, and Ti. In this case, a substitution amount maysatisfy the condition: 0.3≦z≦0.6.

In Formula 2, M′ may be at least one selected from the group consistingof Co, Mn, Ni, Al, Mg, and Ti.

In addition, in Formulas 1 and 2, the oxygen ion may be substituted witha monovalent or divalent anion (A, A′) within a predetermined range,wherein A and A′ may be each independently at least one selected fromthe group consisting of halogens such as F, Cl, Br, and I, S, and N.

Substitution of these anions enables high binding ability with thetransition metals and structural transition of the compound isprevented, whereby the lithium secondary battery may have improvedlifespan. On the other hand, when the substitution amounts of A and A′are too high (t>2), the lifespan of the lithium secondary battery mayrather be deteriorated due to unstable crystal structure.

In the cathode active material of Formula 1 or 2, when O is substitutedwith a halogen or the transition metal such as Ni, Mn, or the like issubstituted with another transition metal (M, M′), the correspondingcompound may be added prior to high-temperature reaction.

The separator is disposed between the cathode and the anode and, as theseparator, a thin insulating film with high ion permeability and highmechanical strength is used. The separator generally has a pore diameterof 0.01 to 10 μm and a thickness of 5 to 300 μm.

As the separator, sheets or non-woven fabrics, made of an olefin polymersuch as polypropylene; or glass fibers or polyethylene, which havechemical resistance and hydrophobicity, or kraft papers are used.Examples of commercially available separators include Celgard seriessuch as Celgard® 2400 and 2300 (available from Hoechest Celanese Corp.),polypropylene separators (available from Ube Industries Ltd. or Pall RAICo.) and polyethylene series (available from Tonen or Entek).

In a specific embodiment of the present invention, the separator may bean organic-inorganic composite separator including a polyolefin-basedseparator and an inorganic material such as silicon. Prior patentapplications of the present applicant disclose the fact that theorganic-inorganic composite separator enables improved stability or thelike of lithium secondary batteries.

The high-output lithium secondary battery including the cathode andanode active materials having the aforementioned particular physicalquantities exhibits capacity with respect to a volume of 0.03 to 0.05Ah/cm³ and energy with respect to a volume of 0.1 to 0.2 Wh/cm³.

These physical quantities may be measured using measurement methodsknown in the art. In particular, the specific surface area may bemeasured by BET, the powder density may be measured using a true densitymeasurement method, and the powder conductivity may be measured bymeasuring sheet resistance after forming a powder into a pellet.

The present invention also provides medium and large-scale batterymodules including the above-described high-output lithium secondarybattery as a unit battery and medium and large-scale battery packsincluding the battery module.

The battery pack may be applied to power sources for electric vehicles,hybrid electric vehicles, and the like, which require high-output andmay also be applied to power storage devices in which it is important tosecure stability and reliability according to high output.

Thus, the present invention provides a device using the battery pack asa power source. In particular, the battery pack may be used as a powersource of electric vehicles, hybrid electric vehicles, plug-in hybridvehicles, or power storage devices.

The configuration of medium and large-scale battery modules and thebattery packs and fabrication thereof are known in the art, and thus, adetailed description thereof will be omitted here.

The cathode may be manufactured by coating, on a cathode currentcollector, a slurry prepared by mixing a cathode mixture including thecathode active material with a solvent such as NMP or the like anddrying and rolling the coated cathode current collector.

The cathode mixture may optionally include a conductive material, abinder, a filler, or the like, in addition to the cathode activematerial.

The cathode current collector is generally fabricated to a thickness of3 to 500 μm. The cathode current collector is not particularly limitedso long as it does not cause chemical changes in the fabricated lithiumsecondary battery and has high conductivity. For example, the cathodecurrent collector may be made of copper, stainless steel, aluminum,nickel, titanium, sintered carbon, copper or stainless steelsurface-treated with carbon, nickel, titanium, silver, or the like, analuminum-cadmium alloy, or the like. The cathode current collector mayhave fine irregularities at a surface thereof to increase adhesionbetween the cathode active material and the cathode current collector.In addition, the cathode current collector may be used in any of variousforms including films, sheets, foils, nets, porous structures, foams,and non-woven fabrics.

The conductive material is typically added in an amount of 1 to 30 wt %based on the total weight of the mixture including the cathode activematerial. There is no particular limit as to the conductive material, solong as it does not cause chemical changes in the fabricated battery andhas conductivity. Examples of conductive materials include graphite suchas natural or artificial graphite; carbon black such as carbon black,acetylene black, Ketjen black, channel black, furnace black, lamp black,and thermal black; conductive fibers such as carbon fibers and metallicfibers; metallic powders such as carbon fluoride powder, aluminumpowder, and nickel powder; conductive whiskers such as zinc oxide andpotassium titanate; conductive metal oxides such as titanium oxide; andpolyphenylene derivatives.

The binder is a component assisting in binding between the activematerial and the conductive material and in binding of the activematerial to the cathode current collector. The binder is typically addedin an amount of 1 to 30 wt % based on the total weight of the mixtureincluding the cathode active material. Examples of the binder include,but are not limited to, polyvinylidene fluoride, polyvinyl alcohols,carboxymethylcellulose (CMC), starch, hydroxypropylcellulose,regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene,polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM),sulfonated EPDM, styrene-butadiene rubber, fluorine rubber, and variouscopolymers.

The filler is optionally used as a component to inhibit cathodeexpansion. The filler is not particularly limited so long as it is afibrous material that does not cause chemical changes in the fabricatedbattery. Examples of the filler include olefin-based polymers such aspolyethylene and polypropylene; and fibrous materials such as glassfiber and carbon fiber.

As a dispersion solution, isopropyl alcohol, N-methylpyrrolidone (NMP),acetone, or the like may be used.

Uniform coating of an electrode material paste on a metallic materialmay be performed using a method selected from among known methods or anew appropriate method in consideration of properties of the electrodematerial. For example, the coating process may be performed by applyingthe paste to the cathode current collector and uniformly dispersing thepaste thereon using a doctor blade. In some embodiments, the applicationand dispersion processes may be implemented as a single process. Thecoating process may be performed by, for example, die-casting, commacoating, screen-printing, or the like. In another embodiment, the pastemay be molded on a separate substrate and then adhered to a currentcollector via pressing or lamination.

The drying of the coated paste on a metallic plate may be performed in avacuum oven at a temperature between 50 and 200° C. for a period of oneday.

The anode may be manufactured by coating the anode active material on ananode current collector and drying the coated anode current collector.As desired, components such as the above-described conductive material,binder and filler may further be optionally added to the anode activematerial.

The anode current collector is typically fabricated to a thickness of 3to 500 μm. The anode current collector is not particularly limited solong as it does not cause chemical changes in the fabricated secondarybattery and has conductivity. For example, the anode current collectormay be made of copper, stainless steel, aluminum, nickel, titanium,sintered carbon, copper or stainless steel surface-treated with carbon,nickel, titanium, or silver, aluminum-cadmium alloys, or the like. As inthe cathode current collector, the anode current collector may also havefine irregularities at a surface thereof to enhance adhesion between theanode current collector and the anode active material. In addition, theanode current collector may be used in various forms including films,sheets, foils, nets, porous structures, foams, and non-woven fabrics.

A lithium salt-containing non-aqueous electrolyte is composed of anon-aqueous electrolyte and a lithium salt. As the non-aqueouselectrolyte, a non-aqueous electrolytic solution, an organic solidelectrolyte, or an inorganic solid electrolyte may be used.

For example, the non-aqueous electrolytic solution may be an aproticorganic solvent such as N-methyl-2-pyrrolidone, propylene carbonate,ethylene carbonate, butylene carbonate, dimethyl carbonate, diethylcarbonate, ethyl methyl carbonate, gamma butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxy ethane, tetrahydroxy franc, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, 4-methyl-1,3-dioxene,diethylether, formamide, dimethylformamide, dioxolane, acetonitrile,nitromethane, methyl formate, methyl acetate, phosphoric acid triester,trimethoxy methane, dioxolane derivatives, sulfolane, methyl sulfolane,1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives,tetrahydrofuran derivatives, ether, methyl propionate, or ethylpropionate.

Examples of the organic solid electrolyte include polyethylenederivatives, polyethylene oxide derivatives, polypropylene oxidederivatives, phosphoric acid ester polymers, poly agitation lysine,polyester sulfide, polyvinyl alcohols, polyvinylidene fluoride, andpolymers containing ionic dissociation groups.

Examples of the inorganic solid electrolyte include nitrides, halidesand sulfates of lithium such as Li₃N, LiI, Li₅NI₂, Li₃N—LiI—LiOH,LiSiO₄, LiSiO₄—LiI—LiOH, Li₂SiS₃, Li₄SiO₄, Li₄SiO₄—LiI—LiOH, andLi₃PO₄—Li₂S—SiS₂.

The lithium salt is a material that is readily soluble in thenon-aqueous electrolyte and examples thereof include LiCl, LiBr, LiI,LiClO₄, LiBF₄, LIB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂, LiAsF₆, LiSbF₆,LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, LiSCN, LiC(CF₃SO₂)₃, (CF₃SO₂)₂NLi,chloroborane lithium, lower aliphatic carboxylic acid lithium, lithiumtetraphenyl borate, and imide.

In addition, in order to improve charge/discharge characteristics andflame retardancy, for example, pyridine, triethylphosphite,triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphorictriamide, nitrobenzene derivatives, sulfur, quinone imine dyes,N-substituted oxazolidinone, N,N-substituted imidazolidine, ethyleneglycol dialkyl ether, ammonium salts, pyrrole, 2-methoxy ethanol,aluminum trichloride, or the like may be added to the electrolyte. Insome cases, in order to impart incombustibility, the electrolyte mayfurther include a halogen-containing solvent such as carbontetrachloride and ethylene trifluoride. In addition, in order to improvehigh-temperature storage characteristics, the electrolyte may furtherinclude carbon dioxide gas, fluoro-ethylene carbonate (FEC), propenesultone (PRS), fluoro-propylene carbonate (FPC), or the like.

BEST MODE

Now, the present invention will be described in more detail withreference to the following examples. These examples are provided onlyfor illustration of the present invention and should not be construed aslimiting the scope and spirit of the present invention.

EXAMPLE 1

A cathode active material prepared by mixingLiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ having an average particle diameter of 0.05μm/mAh with respect to capacity and LiMn₂O₄ having an average particlediameter of 0.14 μm/mAh with respect to capacity in a mixing ratio of35:65, a conductive material, and a binder were prepared in a weightratio of 89:6.0:5.0 and then were added to NMP and mixed therein toprepare a cathode mixture. Subsequently, the cathode mixture was coatedand rolled on an Al foil having a thickness of 20 μm and dried, therebycompleting fabrication of a cathode.

Similarly, carbon having a specific surface area of 0.020 m²/mAh withrespect to capacity, a conductive material, and a binder were preparedin a weight ratio of 92:2:6, added to a mixer, and mixed therein toprepare an anode mixture. Subsequently, the anode mixture was coated androlled on a Cu foil having a thickness of 20 μm and dried, therebycompleting fabrication of an anode.

The cathode, the anode, and a carbonate electrolytic solution containing1M LiPF₆ as an electrolyte were used to manufacture a battery.

In this regard, LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ had a powder conductivityof 1.0×10⁻³ S/cm at a powder density of 2.75 g/cc, LiMn₂O₄ having apowder conductivity of 5×10⁻⁵ S/cm at a powder density of 2.80 g/cc, andthe carbon had a powder conductivity of 30 S/cm at a powder density of1.1 g/cc.

EXAMPLE 2

A battery was manufactured in the same manner as in Example 1, exceptthat the mixing ratio of LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ to LiMn₂O₄ in thecathode active material was 20:80.

EXAMPLE 3

A battery was manufactured in the same manner as in Example 1, exceptthat carbon having a specific surface area of 0.012 m²/mAh with respectto capacity was used instead of the carbon having a specific surfacearea of 0.020 m²/mAh with respect to capacity. In this regard, thecarbon had a powder conductivity of 65 S/cm at a powder density of 1.5g/cc.

EXAMPLE 4

A battery was manufactured in the same manner as in Example 3, exceptthat the mixing ratio of LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ to LiMn₂O₄ in thecathode active material was 30:70.

EXAMPLE 5

A battery was manufactured in the same manner as in Example 1, exceptthat an anode active material prepared by mixing the carbon of Example 1and the carbon of Example 3 in a mixing ratio of 30:70 was used.

EXAMPLE 6

A battery was manufactured in the same manner as in Example 5, exceptthat the mixing ratio of LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ to LiMn₂O₄ in thecathode active material was 20:80.

COMPARATIVE EXAMPLE 1

A battery was manufactured in the same manner as in Example 1, exceptthat the mixing ratio of LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ to LiMn₂O₄ was65:35.

COMPARATIVE EXAMPLE 2

A battery was manufactured in the same manner as in Example 1, exceptthat a mixture of LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ having an averageparticle diameter of 0.12 μm/mAh with respect to capacity and LiMn₂O₄having an average particle diameter of 0.23 μm/mAh with respect tocapacity was used as the cathode active material.

COMPARATIVE EXAMPLE 3

A battery was manufactured in the same manner as in Example 1, exceptthat a mixture of LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ having a powderconductivity of 9×10⁻⁴ S/cm at a powder density of 2.75 g/cc and LiMn₂O₄having a powder conductivity of 5×10⁻⁶ S/cm at a powder density of 2.80g/cc was used as the cathode active material.

COMPARATIVE EXAMPLE 4

A battery was manufactured in the same manner as in Example 1, exceptthat a mixture of carbon having a specific surface area of 0.007 m²/mAhwith respect to capacity and carbon having a specific surface area of0.002 m²/mAh with respect to capacity was used as the anode activematerial.

COMPARATIVE EXAMPLE 5

A battery was manufactured in the same manner as in Example 1, exceptthat a mixture of carbon having a powder conductivity of 10 S/cm at apowder density of 1.1 g/cc and carbon having a powder conductivity of 25S/cm at a powder density of 1.5 g/cc was used as the anode activematerial.

EXPERIMENTAL EXAMPLE 1

Rate characteristics of the batteries manufactured according to Examples1 to 6 and Comparative Examples 1 to 5 were evaluated at a rate of 3 Cvs. 0.2 C and evaluation results are shown in Table 1 below. C-rates ofthe batteries were measured at 1 C and 13 A. Charging and dischargingwere performed between 3.0 and 4.2 V, and charging was measured at aconstant current and a constant voltage (CC/CV) and discharging wasmeasured at CC.

TABLE 1 3 C/0.2 C % Example 1 94.2 Example 2 97.5 Example 3 94.1 Example4 95.8 Example 5 93.5 Example 6 96.0 Comparative Example 1 91.5Comparative Example 2 89.7 Comparative Example 3 88.6 ComparativeExample 4 84.7 Comparative Example 5 86.3

EXPERIMENTAL EXAMPLE 2

After flowing current for 10 seconds, output values of the batteries ofExamples 1 to 6 and Comparative Examples 1 to 5 were calculated usingthe following equations and output characteristics thereof wereevaluated through comparison therebetween. Results are shown in Table 2below.

10 s discharge battery resistance at SOC50%

R=(OCV−V)/I

In the above equation, OCV refers to an open circuit voltage immediatelybefore discharge pulse and V is a cut-off voltage of a 10 s dischargepulse.

10 s discharge power at the different SOC%

P=Vmin(OCV−Vmin)/R

TABLE 2 10 s output Vs. Example 1 (%) Example 1 100 Example 2 106.2Example 3 99.6 Example 4 102.4 Example 5 98.7 Example 6 103.4Comparative Example 1 94.5 Comparative Example 2 92.3 ComparativeExample 3 93.4 Comparative Example 4 91.8 Comparative Example 5 93.7

As shown in Tables 1 and 2 above, it can be confirmed that the batteriesof Examples 1 to 6 had enhanced rate characteristics and outputcharacteristics when compared to the batteries of Comparative Examples 1to 5.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

INDUSTRIAL APPLICABILITY

As described above, the amorphous carbon included in the lithiumsecondary battery according to the present invention has a higher energydensity than that of conventional amorphous carbon and thus, when alithium secondary battery is manufactured using the amorphous carbon,the lithium secondary battery has the same level of capacity as that ofa lithium secondary battery including the conventional amorphous carbonand has a decreased thickness, whereby the fabricated lithium secondarybattery may have enhanced high-output characteristics andlow-temperature characteristics.

1. A high-output lithium secondary battery comprising: a cathodecomprising, as cathode active materials, a first cathode active materialrepresented by Formula 1 below and having a layered structure and asecond cathode active material represented by Formula 2 below and havinga spinel structure, wherein an amount of the second cathode activematerial is between 40 and 100 wt % based on a total weight of the firstand second cathode active materials; an anode comprising amorphouscarbon having a capacity of 300 mAh/g or more; and a separator:Li_(x)(Ni_(v)Mn_(w)Co_(y)M_(z))O_(2-t)A_(t)   (1) wherein 0.8<x≦1.3,0≦v≦0.9, 0≦w≦0.9, 0≦y≦0.9, 0≦z≦0.9, x+v+w+y+z=2, and 0≦t<0.2; M refersto at least one metal or transition metal cation having an oxidationnumber of +2 to +4; and A is a monovalent or divalent anion,Li_(a)Mn_(2-b)M′_(b)O_(4-c)A′_(c)   (2) wherein 0.8<a≦1.3, 0≦b≦0.5, and0≦c≦0.3; M′ refers to at least one metal or transition metal cationhaving an oxidation number of +2 to +4; and A′ is a monovalent ordivalent anion
 2. The high-output lithium secondary battery according toclaim 1, wherein the amorphous carbon is one selected from the groupconsisting of a first carbon having a specific surface area of 0.01 to0.031 with respect to capacity and a second carbon having a specificsurface area of 0.0035 to 0.017 with respect to capacity or a mixturethereof.
 3. The high-output lithium secondary battery according to claim2, wherein the first carbon has a powder conductivity of 15 S/cm orgreater to less than 100 S/cm at a powder density of 1.0 to 1.2 g/cc. 4.The high-output lithium secondary battery according to claim 2, whereinthe second carbon has a powder conductivity of 30 S/cm or greater toless than 100 S/cm at a powder density of 1.4 to 1.6 g/cc.
 5. Thehigh-output lithium secondary battery according to claim 1, wherein thefirst cathode active material has an average particle diameter of 0.03to 0.1 μm/mAh with respect to capacity.
 6. The high-output lithiumsecondary battery according to claim 1, wherein the first cathode activematerial has a powder conductivity of 1×10⁻³ S/cm or greater to lessthan 10×10⁻³ S/cm at a powder density of 2.65 to 2.85 g/cc.
 7. Thehigh-output lithium secondary battery according to claim 1, wherein thesecond cathode active material has an average particle diameter of 0.1to 0.2 μm/mAh with respect to capacity.
 8. The high-output lithiumsecondary battery according to claim 1, wherein the second cathodeactive material has a powder conductivity of 1×10⁻⁵ S/cm or greater toless than 10×10⁻⁵ S/cm at a powder density of 2.65 to 2.85 g/cc.
 9. Thehigh-output lithium secondary battery according to claim 1, wherein, inFormula 1, M is at least one selected from the group consisting of Al,Mg, and Ti and, in Formula 2, M′ is at least one selected from the groupconsisting of Co, Mn, Ni, Al, Mg, and Ti.
 10. The high-output lithiumsecondary battery according to claim 1, wherein, in Formulas 1 and 2, Aand A′ are each independently at least one selected from the groupconsisting of halogens, S, and N.
 11. The high-output lithium secondarybattery according to claim 1, wherein the lithium secondary battery hasa capacity of 0.03 to 0.05 Ah/cm³ with respect to volume and an energyof 0.1 to 0.2 Wh/cm³ with respect to volume.
 12. The high-output lithiumsecondary battery according to claim 1, wherein the separator is anorganic-inorganic composite separator.
 13. A battery module comprisingthe lithium secondary battery according to claim 1 as a unit battery.14. An electric vehicle or hybrid electric vehicle using the batterymodule according to claim 13 as a power source.
 15. A power storagedevice using the battery module according to claim 13 as a power source.